What I'm interested in learning is how the Boulder DA's office tracked him to Thailand.
Internet cafe's are the norm in Bangkok or Thailand. Tourists use them to stay in touch with family and friends while on holiday. I always use the same one or two locations when I am there. It costs about 1 thb per minute or 2 cents a minute.
Well, they are the norm for non-residents. He had an apartment and may well have had his own internet connection but I doubt he was tracked either way. I expect he used a web based email client like Yahoo.
I don't think he was being secretive about his location - I did not see anything in the reports that indicated that. There would be lots of ways to find him if he was, like airline bookings. If they suspected he was in Thailand then the feds would have requested the Thais to go through their records. Foreigners are required to register with Thai immigration if staying more than 90 days. Hotels and even apartments have to submit a similar form on any foreigners staying with them although small apartments may not (and will be fined if caught).
I'm assuming it was his communication with the college professor in Boulder that revealed his whereabouts. I can't help but think the DA's office in Boulder isn't stupid enough to botch an arrest in this high profile case. They've got more on this guy then mear speculation.
Also, considering California has open warrants for his arrest, if the Boulder DA didn't have anything, or enough to arrest they'd contact CA to make the arrest and after that took place questioned him about the JonBenet case. Instead, they went for the arrest.